The subject invention generally relates to a retroreflective coating system and a method of providing the retroreflective coating system on a substrate. More specifically, the subject invention relates to a cross-linkable, retroreflective coating system that includes retroreflective microspheres for wet-on-wet application to an automotive body panel.
Use of retroreflective and reflective microspheres is known. For instance, U.S. Pat. No. 5,650,213 incorporates retroreflective microspheres into retroreflective compositions that are used on fabrics and the like to enhance the retroreflectivity of the fabrics. Clothing made of retroreflective fabric improves the safety of pedestrians who wear the clothing at nighttime because the pedestrians are more visible to others. Use of reflective microspheres in automotive and other coating systems is also known in the art. For instance, U.S. Pat. No. 6,242,056 incorporates reflective microspheres into reflective, heat-cured coating systems to enhance the light emission, refraction, and diffusion of the coating system.
The conventional use of retroreflective and reflective microspheres in conventional coating systems is inadequate for various reasons. Many compositions that are used to form the coating systems with the retroreflective microspheres are not cross-linkable. As a result, these compositions are not suitable for automotive coating systems where durability and the physical integrity of the coating system, relative to weathering and exposure, is paramount. Furthermore, many coating systems, such as the coating system of the ""056 patent, are not retroreflective coating systems. Instead, these systems only incorporate reflective microspheres that primarily serve to enhance various aesthetic properties of the coating system, such as color. These systems are also not ideal for automotive coating systems. Simply stated, because these systems are not retroreflective, they do not optimally enhance the visibility of a vehicle having the coating system and, as a result, they do not optimally enhance the safety of pedestrians who need to watch for vehicles at nighttime for their own protection.
The conventional use of retroreflective and reflective microspheres in conventional coating systems is also inadequate because the microspheres in these coating systems must be completely encapsulated within a particular film layer to be able to produce the desired light emission, refraction, and diffusion. An example of such a coating system is disclosed in the ""056 patent. These conventional coating systems of the prior art typically require cures, or bakes, between each film layer of the coating system (i.e., multiple, sequential cures) to achieve complete encapsulation of the microspheres within the particular film layer. These systems also typically require cures between each film layer to ensure that the coating system, having the microspheres, achieves a satisfactory gloss. These coating systems are inadequate because they do not allow for wet-on-wet application of the various film layers that make up the coating system. Wet-on-wet application of the various film layers to make up the coating system is not feasible for the coating systems of the prior art because these systems only achieve satisfactory gloss with cures between each film layer. It is widely known throughout the art that any method requiring cures for each film layer of a coating system is time consuming and expensive because costly ovens must be used for each cure.
In sum, the coating systems and compositions of the prior art, primarily the uses of the retroreflective and reflective microspheres in these coating systems and compositions, are characterized by one or more inadequacy. As a result, it is desirable to implement a method of providing a retroreflective coating system that includes applying the coating system wet-on-wet to a substrate, such as an automotive body panel. The retroreflective coating system is cross-linkable, includes retroreflective microspheres, and achieves a satisfactory gloss with wet-on-wet application to the substrate.
A retroreflective coating system and a method of providing the retroreflective coating system are disclosed. The retroreflective coating system is provided on a substrate. The method includes the steps of applying a color-providing composition and an at least partially-transparent clearcoat composition. Either one, or both, of the color-providing composition and the clearcoat composition is cross-linkable. Furthermore, either one, or both, of the color-providing composition and the clearcoat composition includes retroreflective microspheres. The retroreflective coating system includes a color-providing film layer formed from the color-providing composition, and an at least partially-transparent clearcoat film layer formed form the clearcoat composition.
The color-providing composition is applied to the substrate. Application of the color-providing composition to the substrate forms an uncured film layer of the color-providing composition. The method also includes the step of applying the clearcoat composition to the uncured film layer of the color-providing composition. More specifically, the clearcoat composition is applied to the color-providing composition wet-on-wet. An uncured film layer of the clearcoat composition is formed on the uncured film layer of the color providing composition upon application of the clearcoat composition.
Accordingly, the subject invention offers a retroreflective coating system and a method that provides a retroreflective coating system that is cross-linkable and that includes retroreflective microspheres for wet-on-wet application of the coating system to a substrate. Because the retroreflective coating system of the subject invention is cross-linkable, it is durable. Furthermore, the retroreflective coating system provided according to the method of the subject invention, is able to achieve satisfactory gloss and retroreflectivity for the substrate even with wet-on-wet application of the various film layers of the coating system. As a result, the method of providing the retroreflective coating system is cost-efficient, and the retroreflective coating system optimally enhances the visibility of the substrate to others to ensure safety.